In this case, a medical history was identified for this non-illness based film after inquiry with the patient.

If this was a de-novo lesion a differential for a lucent rib lesion should be followed. In fact, a popular film for fellowship viva examinations.

Because:

1.  one needs to spot it (bones important review area of CXR); tests observation

2.  give a sensible description of the findings; test of candidates descriptive skills

3.  give a sensible differential; several for a lucent rib lesion from benign to malignant

4.  check the candidate's advice/management skills

'What would you do next'? Tests if practical advice is given to help the clinician.